In various medical procedures including endoscopic examination of a patient's abdominal cavity, and/or the draining of fluids therefrom, it is necessary that easy access be gained to the abdominal cavity. Typically, a surgical instrument known as a trocar that consists of a sharp pointed instrument, may be used to penetrate the abdominal wall to create an access hole therethrough into the abdominal cavity. Another instrument known as a Veress needle typically consists of a hollow outer needle having the end opposite the pointed end rigidly secured to a handle-like housing. A tube or hollow stylet is slidably carried within the hollow needle. One end of the tube is typically secured to one end of a piston-like hollow plunger slidably retained within a plunger cylinder formed in the handle-like housing. The other end of the plunger is typically attached to one end of a spring, the other end of which is connected to the top end of the plunger cylinder. A centrally located axially directed hole through the housing connects the interior of the plunger cylinder to a port at the end of the housing for receiving a petcock or valve mechanism. The other end of the tube typically projects beyond the needle point, with the tube having a gas exit hole through the side of the tube proximate the tip. The tube is oriented within the needle to insure that the gas exit hole of the tube is not blocked by the needle when the tubing end is protruding from the needle via the spring biasing. The free or protruding end of the hollow tube is closed off, typically via a plug.
In using such a known Veress needle, a physician pushes the free end of the tube against the abdomen of a patient. The tube retracts via the spring biasing, permitting the needle to be forced through the abdominal wall into the abdominal cavity, whereafter the free end of the inner tube pops out or extends from the needle via the spring biasing, thereby exposing the gas exit hole. This, of course, assumes that the needle is in an open area of the abdominal cavity, and is not pushing against some internal organ, which would prevent the inner tube from so popping out or moving to its extended position relative to the needle. The physician can then connect a gas line to the valve or petcock, and cause gas to enter into the Veress needle, pass through the tube and exit out of the gas exit hole of the tube into the abdominal cavity for insufflating the abdominal cavity. Alternatively, fluid can either be forced into or sucked from the abdominal cavity through use of the Veress needle.
There are many examples in the prior art of Veress needle and trocar instruments. A number of such prior instruments are discussed below.
Bauer et al., U.S. Pat. No. 4,379,458, teaches a trocar sleeve assembly that includes an interior chamber having a ball valve assembly. When a trocar is passed through the sleeve assembly, the ball valve is opened via passage of the trocar and retained in the open position so long as the trocar is present. When the trocar is removed, the ball is resiliently biased to move back into a position for closing off the trocar channel leading from the interior of the chamber to the uppermost portion of the trocar sleeve. It appears that any gases that passed through the sleeve or the trocar would by necessity have to pass over interior components, such as the ball itself, and a leaf-like spring 11 before entering the abdominal cavity.
Moll, U.S. Pat. No. 4,601,710, discloses a trocar assembly which includes a spring biased outer tubular protective shield that is extended beyond the end of the piercing tip of a trocar obturator enclosed within the shield. When the trocar is being inserted through the wall of a body cavity, the shield is forced back to its retracted position for permitting the piercing tip of the trocar to be forced through the abdominal wall, whereafter the shield then moves back over the piercing tip. A port is provided in the associated trocar assembly for permitting an insufflating gas to be injected into the port, and through the trocar tube into the abdominal cavity. However, the gas must pass through springs and other mechanical mechanism that are not easily sterilized, prior to entering the abdominal cavity.
Moll et al., U.S. Pat. No. 4,654,030, discloses a relatively complicated trocar assembly. An outer tubular member of the trocar assembly for carrying an elongated obturator, has one end that is fitted into a body member including a flap valve that locks into a slot in the trocar tube for preventing that end from moving out of the holding body. A manual pivot is provided for permitting the flap valve to be moved out of engagement with the slot of the trocar tube, for permitting release of the same. Spring biasing is provided for the trocar tube. A stopcock port 89 is included on the side of the holding body for permitting gases to be injected through the trocar tube into a body cavity.
Warring, U.S. Pat. No. 4,808,168, teaches a pneumoneedle. As shown in the exploded assembly diagram of FIG. 2, gas is injected through the stopcock 12 and must flow around an interior bias spring 13, and the outside of the stylet 14, in passing through the hollow needle 16 into a body cavity. In FIG. 5, an alternative embodiment shows gas passing through the spring chamber 32 and a hallow stylet 36, to exit from a hole 42 into the abdominal cavity. Note that a plug 40 is used to seal the leading end 38 of the lumen 39.
Adair, U.S. Pat. No. 4,869,717, discloses a disposable trocar including a removable gas insufflation needle which can be used to inflate a body cavity with an inert gas. As shown in the figures, a tubular rod 16 has an opening 22 at its forwardmost end, and is slidably mounted within a needle 10. Tubular member 16 is spring biased via a spring 24 captively retained within a lower portion of a housing 36. Any gases passing through the tube 16 must flow over the spring before entering the tube 16.
Lander, U.S. Pat. No. 4,902,280, discloses a trocar assembly that includes a leaf spring mechanism for insuring that a protective outer sheath cannot be inadvertently retracted. Other spring biasing is provided for biasing a tube 16 surrounding a stylet 14. The inner stylet is rigidly connected at one end to an interior portion of a housing.
Holmes, U.S. Pat. No. 4,931,042, teaches a trocar assembly which includes an obturator 22 enclosed in a central portion of the extended portions of the trocar assembly that appears to be a solid rod-like member having a piercing tip 24. Gases must flow over this rod or between the inner and outer walls of outer and inner sheath members. Similar to the previous patent, a leaf spring latching mechanism is included within the main housing of the trocar assembly. Also, a number of other lever-like latching mechanisms are included therein.
The present inventors observed a number of problems with prior Veress type needle assemblies. One problem is that insufflating gas passing through such prior assemblies typically must pass over springs and other mechanical mechanisms that are not easily sterilized, and could cause contaminants to flow through the tube with the gas into the abdominal cavity. Also, in certain of the prior designs undesirable pressure vessels may be created within the assembly as the gases pass through the assembly. This is especially true when the end of the tubing inserted into the abdominal cavity becomes blocked, causing gas pressure to build up within the needle assembly. Also, when such blockage may occur due to body debris, for example, the prior needle assemblies do not facilitate clearing of such debris away from the gas exit hole. Also, prior instruments do not provide any means for warning a physician that the pointed end of a Veress needle, for example, is against an abdominal wall, or an internal organ.